Our research project is centered on using the process of ovarian development to delineate hormone-triggered programs of differentiation at the cellular and molecular levels. We are using recombinant DNA technology, to isolate, localize, characterize and sequence the vitellogenin structural genes of D. melanogaster and D. grimshawi. These genes will then be used to study the interactions between the process of vitellogenesis and the aging of the flies. By a combination of biological, biochemical, immunochemical, and electron microscopical methods of analysis, we will determine the nature of the interactions, and the level at which they operate. Several female-sterile mutant strains will be screened to identify age-dependent mutants and also those which are deficient for vitellogenin synthesis or which synthesize modified vitellogenin proteins. These latter ones will be used for studying the regulation of vitellogenin gene expression.